73ef4ff3
 Hu Chunming
提交三方库
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// Copyright Louis Dionne 2013-2022
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
#include <boost/hana/assert.hpp>
#include <boost/hana/core/to.hpp>
#include <boost/hana/equal.hpp>
#include <boost/hana/filter.hpp>
#include <boost/hana/integral_constant.hpp>
#include <boost/hana/length.hpp>
#include <boost/hana/mod.hpp>
#include <boost/hana/range.hpp>
#include <boost/hana/slice.hpp>
#include <boost/hana/tuple.hpp>
#include <boost/hana/type.hpp>
namespace hana = boost::hana;
using namespace hana::literals;
// Slice a contiguous range
constexpr auto xs = hana::make_tuple(0, '1', 2.2, 3_c, hana::type_c<float>);
static_assert(
hana::slice(xs, hana::tuple_c<std::size_t, 1, 2, 3>) ==
hana::make_tuple('1', 2.2, 3_c)
, "");
// A more complex example with a non-contiguous range
constexpr auto letters = hana::to_tuple(hana::range_c<char, 'a', 'z'>);
constexpr auto indices = hana::to_tuple(hana::make_range(hana::size_c<0>, hana::length(letters)));
auto even_indices = hana::filter(indices, [](auto n) {
return n % hana::size_c<2> == hana::size_c<0>;
});
BOOST_HANA_CONSTANT_CHECK(
hana::slice(letters, even_indices) == hana::tuple_c<char,
'a', 'c', 'e', 'g', 'i', 'k', 'm', 'o', 'q', 's', 'u', 'w', 'y'
>
);
int main() { }
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